1. Field of the Invention
The present invention generally relates to the field of manufacture and assembly of circuit boards. More specifically it relates to a tape guide for guiding a carrier tape in a component mounting machine, a tape magazine for receiving the tape guide, and a system including the tape guide and the tape magazine.
2. Description of Background Art
Generally, within the field of manufacture and assembly of circuit boards, electronic components are fed to a component mounting machine for mechanically and/or electrically mounting the components onto a circuit board. These surface mounted components are often delivered spaced apart along the length of a component tape, which consists of a lower carrier tape provided with compartments, one for each component, and an upper cover, or cover tape or protective tape. After positioning the electronic components in the corresponding compartments, the cover tape is attached to the carrier tape, and the component tape is wound on a component reel. The attachment of the cover tape to the carrier tape can, for instance, be performed by providing either the cover tape or the carrier tape with adhesive areas, or by fusing the cover tape to the carrier tape. Then, the component reel is transferred to a component mounting machine, which feeds a component to a certain predetermined picking position where it can be picked, or collected, by a pick-up head. WO 86/00778 shows a cassette magazine for a component mounting machine using the above described method.
According to the method conventionally used within the art, the loading of a component tape in a component mounting machine involves the following steps. Placing the component tape reel into the tape holder of a component mounting machine, or into a tape magazine of a component mounting machine; introducing the free end of the component tape into a feeding mechanism, provided in the machine or in the magazine, such that feeding pins engage corresponding holes provided in the component tape; separating, by hand, the end of the cover tape from the end of the carrier tape for a distance sufficient for the cover tape to be engaged with a cover tape handling means; and lowering a locking mechanism over the carrier tape for holding the carrier tape against the feeding mechanism.
Prior to the picking of the components, each component has to be exposed so as to make it available for picking. Conventionally, this is achieved by removing the cover tape from the carrier tape. The cover tape is then fed away by a separate cover tape handling means in order for the cover tape not to disturb the picking of components. Generally, the cover tape handling means comprises a winding hub on which the cover tape is wound. Additionally, when unloading the component tape from the component mounting machine, or the tape magazine, the winding hub has to be cleared of the cover tape.
A considerable length of the end of the cover tape has to be separated from the end of the carrier tape in order to bring the cover tape end to a cover tape handling means. Thus, the first decimetres of a new carrier tape are not provided with components. Otherwise, numerous components would be wasted during loading. However, when reloading a tape reel that already has been partly used, the tape is provided with components throughout, and consequently a large number of components may be wasted.
U.S. Pat. No. 4,820,369 discloses an alternative method and device for exposing the components at the picking position. According to the embodiments shown in FIGS. 7 and 8, the cover tape is separated from the carrier tape along one side of the carrier tape only, while the cover tape remains adhered to the carrier tape along the other side. Thereby, the need for separate cover tape handling means is reduced or even eliminated. Using this method, the distance of cover tape that has to be removed from the carrier tape when loading or reloading a carrier tape can be reduced, but not eliminated, thus there would still be some component waste. Further, there would also still be components wasted when unloading a carrier tape from the compartments where the components have been exposed but have not yet been picked-up. Even though this method would be preferred as compared to using a separate cover tape handling means, the loading of the carrier tape into the component mounting machine and the device for exposing the components must still be performed individually for each carrier tape. During this time, the component mounting machine must be shut off.
As realised from the above, the loading of a component tape in a component mounting machine is a time-consuming and complicated process that has to be performed every time a new component has to be added to the circuit board manufacturing process, and every time an empty component tape has to be replaced. This negatively affects the overall time efficiency of the manufacturing process and, hence, the overall costs. Additionally, when using a winding hub, or the like, for handling the cover tape, the required time for the loading process is further increased, and the unloading of the component tape includes the additional step of clearing the winding hub of the cover tape. Furthermore, there is high risk of a considerable component waste with the loading method according to prior art.